Selective formation zone anchor



Jan. 26, 1965 Filed April 24, 1962 W. N. SUTLIFF SELECTIVE FORMATION ZONE ANCHOR 3 Sheets-Sheet 1 /1/ g INVENTOR,

WAM/EN San/pff,

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Jan. 26, 1965 w. N. su'rLlFfl' 3,167,128

SELECTIVE FORMATION ZONE ANCHOR Filed April 24, 1962 5 Sheets-Sheet 2 'al v;

INVENTOR.

myA/E M 307-1. lFF,

Jan. 26, 1965 w. N. sUTLlFF 3,167,128

sELEOTIvE FORMATION ZONE ANCHOR Filed April 24, 1962 5 Sheets-Sheet 5 INVENTOR. My/ve .M 50u/FF,

BY l

fram/Eg United States Patent O 3,167,l2tl ELECTEVE FQRMATEN ZGNE ANCHR Wayne N. Sutlitll, 2931 Pierce Road, Ealrerslield, Calif. Filed Apr. 24, 1962, Ser. No. 199,266 9 Claims. (Cl. 16d-2M) This invention relates to mechanisms for setting one or more packers in a deep well and is particularly useful in setting an open wall packer.

Open hole wall engaging anchor means have been heretofore provided to halt the downward movement of a tool embodying an expansive packer, such as a formation testing tool, whereby subsequent downward pressure through the drill string will expand the packer and pack olf the space between the tool and the well wall. Such anchor means were subject to defective operation due to premature expansion during the lowering of the tool into the well. Furthermore, former anchor means provided for the purpose noted, was wanting in the ruggedness called for in setting and resetting such an expansive packer.

lt is an object of the present invention to provide `a selective formation zone anchor for use in supporting an open hole packer while setting the same, which anchor will be relatively proof against being inadvertently allowed to expand prematurely while running the same into the well.

Another object of the invention is to provide such a selective formation zone anchor which is not only efficientin its engagement with the formation comprising the wellwall but ruggedly designed to withstand hard usage. t

It is another object of the invention to provide such a selective formation zone anchor which is adapted to be set at a plurality of different levels in a well bore without the necessity of withdrawal therefrom so that if the setting of a packer at a given level is found unsatisfactory the zone anchor may be retracted out of engagement with the well bore, moved to a different leveland there expanded to facilitate expansion of the packer at a different location in the well.

A further object of the present invention is to provide a locking device adapted to be associated with a selective formation zone anchor which will positively prevent expansion of said anchor before the latter has reached a predetermined depth in a well bore into which it is being introduced, thus preventing said zone anchor being prematurely set while being run into the well.

The manner of accomplishing the foregoing objects as well asfurther objects and advantages will be made manifest in the following description taken in connection with the accompaying drawings, in which:

FIG. 1 is a vertical elevational view of a preferred embodiment of the invention as being run into a well bore with portions of the structure brokenaway to illustratecertain parts thereof in section. e

FIG. 2 is a view similar to `FlG. 1 and shows the operation of the `l-slot` releasing means so as to release the detent jaws of the device from retracted position preparatory to expanding said jaws.

FIG. 3 is a view similar to FG. 2 and illustrates'the next step in the process of operating the invention in which the detent jaws are spread apart so that they dig into the wall of the well bore, as weight is placed downwardly on the anchor from above, so that a packer assembled in the string above the anchor may be expanded by such weight to seal off said well bore as for the purpose of Conducting a formation testing operation by a testing tool associated with said packer'.

FIG. 4 is an enlarged horizontal sectional view taken on the line lll-liand looking upwardly at the detent t Ul 3,157,128 Patented Jan. 26, 1965 ice jaws of the invention while these are in retracted position as shown in FIG. 2.

FIG. 5 is a similar View looking upwardly at said detent jaws while the latter are expanded as shown in FIG. 3.

FIG. 6 is an enlarged sectional detail View of aportion of FlG. 1 and illustrates the manner in which the detent jaws are held in retracted position while the anchor of the invention is beingintroduced into a well bore.

PEG. 7 is a perspective view of one of the detent jaws of the invention disassembled from said anchor.

8 is a perspective View of a modifiedV form of detcnt jaw which is adapted to be used in the anchor of the invention.

FiG. 9 is a fragmentary sectional view of a modified form of the detent jaw releasing means of the invention involving a threaded connection between the mandrel tube and the spring cage thereof, and showing this as the anchor is being lowered into a well bore.

FIG. 10 is a view similar. to FIG. 9 showing said threaded connection unscrewed by rotation of said mandrel tube from the ground level, thereby releasing the head sub allowing this to be lifted to elevate the de'tent jaws out of engagement with the conical member of` said cage and free said jaws for spreading.

FiG. ll is a view similar to FlG. l() showing the tube being lowered to effect the spreading apart of said jaws by their re-engaging said conical member, after a slight rotation of said jaws relative to said member.

FIG. 12 is an enlarged sectional fragmentary view of a hydrostatic lock of the invention in locking position thereby preventing inadvertent operation of the anchor during descent through the well bore, and prior to its arrival approximately at the level where a formation test is to be made.

Referring specifically to the drawings, the preferred embodiment of the invention disclosed in. FIGS. 1, 2, 3, 4, 5, 5 and 7, comprises a selective formation zone anchor l5. This anchor is normally suspended on the lower end of a drill string le which has assembled therein shortly above the anchor 15, a packer. (not shown) and, immediately thereabove, a formation testing tool (not shown). The object of the anchor l5 is to support the packer by engagement of the anchor with the wall of a well bore 17 so that the packer may be expanded by the weight of the drill string into sealing relation with the well bore 17 an-d by this seal render the testing tool effective in running the desired formation test.

The anchor. l5 includes a head sub 18 having female threads 19 into which the lower end of the drill string 16 screws andl female threads 2@ into which the threaded' The upper end of an anchor mandrel tube 21 screws. lower end of the tube Zlimay be connected by a collar 22 to a perforated tube (not shown) for conducting well liquid from below the aforesaid packer. to the testing tool in the drill spring 16, or the tuber21 may be closed as by` capping its lower end, to facilitate a formation test being run on a zone located between a pair of packers installed in the drill string le.

The head sub 18 has formed on its lower end a pair of downwardly extending jaw mounting lugs 23 these having horizontal holes 24 for installing pivot pins 25 therein.

Pivotally mounted at their upper ends on the pins 25 is a pair of detent jaws 3l? these jaws preferably have semicylindrical outer surfaces 31 so that when the two jaws are placed together (FGS. l and 2) they form acylinder of approximately the same outside diameter as the head sub lil. The jaws 3@ are hollowed out internally so that when they are placed together about the mandrel tube 21 these jaws present iiuted faces 32 to the mandrel tube while `allowing the surfaces 31 to form a cylindrical surface concentric with said tube and yet also afford substantial vertical hollow spaces 33 on opposite sides of the tube 21 and symmetrical with the vertical plane on which the two jaws 38 meet when they are so positioned against the tube 21. The spaces 33 are approximately triangular in cross section as clearly shown in FIG. 4.

Formed in the upper ends of detent jaws 38 are deep grooves 34 having parallel side walls and slidably receiving the jaw mounting lugs 23. Holes 35 are bored in the arms 36 formed by the grooves 34 in the upper portions of each of the jaws so that when these jaws are slipped upwardly over the lugs 23 and iitted snugly inwardly against the tube 21, the holes are in alignment with the holes 24 in the lugs 23 so that the pivot pins 25 may be inserted through both of these holes thereby pivotally mounting the jaws on the lugs 23. Tapped holes 37 are provided in outer end portions of the holes 35 to receive screws 38 -to retain the pivot pins 25 properly centralized in the holes 35 and 24. Lower ends of jaws 38 have semi-frusto-conical hollows 39 which produce arcuate sharp cutting edges 40 on said jaws. Each of the jaws 30 has a hole 41 which is parallel with the axis of the semicylindrical face 31 thereof this hole forming a pocket for receiving a combined jaw retaining and bore wall engaging spike 45, these spikes being retained against withdrawal by set screws 46. The spikes 45 may be solid 0r they may be tubular as shown in the drawings and have sharpened lower ends so as to readily penetrate the wall of the well bore 17 as shown in FIG. 3.

Rotatable and slidable axially on the mandrel tube 21 is an expansive spring cage 47 which includes upper and lower collars 48 and 49 which are united by an annular series of outwardly bowed leaf springs 50 having their ends secured by screws S1 respectively to said upper and lower collars. The upper collar 48 includes an inner sleeve 53 having an external radial iiange 54 at its lower end, the upper end portion of said inner sleeve being turned down to form a shoulder 55 and having an annular recess 68 provided therein. The upper collar 48 also includes an outer sleeve 61, to which springs 58 are connected, said sleeve being rotatably mounted on the inner sleeve 53 between the external flange 54 and the shoulder 55. Upper collar 48 also includes a hollow frusto-conical member 62, which is rotatably mounted on the upper end of the inner sleeve 53 and retained in place thereon by screws 63 provided on the member 62 so as to extend into the annular recess 60 (FIG. 6). The member 62 is thus not only mounted on inner sleeve 53 so as to be freely rotatable relative thereto but so as to co-operate with the external iiange 54 on said inner sleeve to retain the outer sleeve 61 of upper collar 48 in rotatable relation with the inner sleeve 53 by trapping the same between external flange 54 and member 62.

The lower portion of member 62 has an external cylindrical surface 64 of approximately the same outside diameter as the head sub 18, and an upper frusto-conical surface 65 which is provided with a pair of vertical holes 66 into which the jaw retaining spikes 45 extend when the anchor 15 is assembled 4as shown in FIG. 1. A hole 67 is provided axially in the nose of the member 62 which slidably receives the tube 21.

Associated with the tube 21 and the lower collar 49 of the expansive spring cage 47 is a J-slot locking means 68 for retaining theivarious elements of the anchor 15 assembled as shown in FIG, 1 until the operator desires to release the jaws 30 from the restraint imposed by the spikes 45 extending into vertical holes 66 in the member 62. The locking means 68 includes a sleeve 69 which is formed integral with the lower collar 49 of the expansive spring cage 47 and extends upwardly within the latter, this sleeve having a pair of oppositely disposed J-slots 7 tl each of which includes a short vertical slot 75, a long vertical slot 76 which has a flared open mouth at its upper end, the slots 75 and76 being connected by a horizontal slot 78. The locking means 68 also includes a pair of screw pins 79 which screw into threaded holes provided in the tube 21 and are lodged in the short vertical slots 75 when the anchor 15 is assembled for introduction into a well as shown in FIG. l.

Operation As already noted, the selective formation zone anchor 15 is particularly useful in connection with formation zone testing in which one or more packers are assembled with a testing tool in a drill string 16 with the anchor 15 suspended on the lower end of the latter, and the assembly is then introduced into a well bore 17.

Upon the arrival of the testing tool at the level in the well bore where it is desired to make a test, the operator at the ground level halts downward movement of the drill string 16 and lifts on this just enough to lift the screw pins 79 upward in the short vertical slot 75 until they are opposite the short horizontal slot 78 in the sleeve 69. The drill string is then rotated a quarter turn anticlockwise to bring the pins 79 into the long vertical slot 76. This manipulation of the tube 21 relatively to the expansive spring cage 47 is facilitated by the friction between the latter and the wall of the well bore 17 so that substantial pressure must be applied through the drill string 16 to the spring cage 47 either to move the latter longitudinally in the well bore or to rotate the spring cage in said bore. In the absence of the application of such pressure, the spring cage 47 remains in a fixed position in the bore.

With the pins 79 located in the vertical slots 76 in the sleeve 69, the operator lifts on the drill string 16 until the head sub 18 and jaws 30 suspended therefrom are lifted free of the frusto-conical member 62 as shown in FIG. 2. The operator now rotates the drill string 16 slightly so as to offset the spikes 45 relatively to the vertical holes 66 in the member 62 as suggested in FIG. 2. The drill string 16 is now lowered to bring the spikes 45 into engagement with the frusto-conical surface 65 of the member 62 which starts swinging the detent jaws 30 Outwardly about their pivots on the head sub 18. The operator then continues to lower the drill string 16, while rotating the string to return the pins 79 back into the vertical slots 76 and eventually reaching the position shown in FIG. 3 which shows the detent jaws 30 swung outwardly by engagement with the surface 65 and applying weight to the spring cage 47 so as to force this down the hole while pushing the spikes 45 land arcuate cutting edges 40 of the detent jaws 30 so as to progressively set the anchor 15 in a given position in the well bore 17 beyond which it cannot be easily forced downwardly.

When the anchor 15 has been thus set in a iixed position in the well bore 17, the operator merely has to continue to lower the drill string 16 in order to set the one or more packers included in the latter whereupon everything will be in order for starting the formation test through operation of the testing tool included in the string.

. One of the great advantages of the selective formation zone anchor 15 is that, in the event the iirst choice of a level for accomplishing the formation test turns out to be disappointing, or if, for any reason, a series of tests are desired to be run in the same bore at different levels, the iirst test has been made at the lowermost of these levels, then, subsequent tests may be made by (1) lifting on the drill string 16 to withdraw the detent jaws 30 from their set positions engaging the walls of the well bore 17, (2) pulling the anchor 15 upwardly until the testing tool has arrived at the location for the new test and (3) repeating the operation of setting the anchor as above described s0 as to make the test at the new level.

When withdrawing the jaws 30 from locking relation with the wall of the well bore as shown in FIG. 3, the jaws are entirely above the frusto-conical member 62 and thus are free to swing inwardly to the positions in which they are shown in FIG. 2 and so pass upwardly through the well bore 17 without any resistance to the anchor 15 being lifted, along with the rest of the apparatus, to the new location for making a test. The friction between the expansive spring cage 47 and the wall of the well bore 17 is never great enough to retard the operations of the drilling operator more than just enough to facilitate his manipulation of the mandrel tube 21 both rotationally and axially relative to the cage 47 and the elements mounted thereon.

The double free-wheeling rotatable relation between the expansive spring cage 47 and the frusto-conical member 62 mounted on the upper end thereof is merely to make doubly sure that the latter member will always be freely rotatable relative to said spring cage. Obviously, if the free rotatability of the member 62 on the spring cage 47 were ever to be prevented as by the spaces between these two members being choked with sand, it would not be possible to release the jaws 30 from the position in which these are shown in FIG. 1 to the position in which they are shown in FIG. 2 because it is necessary to rotate the anchor mandrel tube 21 relative to the spring cage 47 to accomplish this and this can only be done by the member 62 being rotatable relative to said cage.

FIGS. l, 2 and 3 represent the anchor 15 of the invention drawn in true scale relation with a well bore 17 of about the diameter that this tool is most often used in. This relationship involves a tool diameter of approximately 51/2 inches and a well bore diameter of approximately 6% inches. The length of the detent jaws 30 used in this situation is 4 inches. This same tool has been operated in well bores of a larger diameter, this being, in one instance, 11% inches. In this particular case, detent jaws 30 were used which are 6% inches long, and a very good setting action was obtained.

It is not always possible to know in advance the exact size of the bore in which the anchor will be set and it is thus sometimes set in a portion of the bore a good deal larger than expected so that the jaws 349 swing outwardly into horizontal positions. In no case, however, has this contingency resulted in a failure of the anchor to properly function.

An alternative modication of the means for temporarily preventing longitudinal movement between the anchor mandrel tube 21 and the expansive spring cage 47 is illustrated in FIGS. 9, l and l1. This constitutes a screw releasing device 8d and includes a key Sl longitudinally set in the tube 21, a sleeve S2 counterbored at its upper end to hold the key 81 in its key seat and resting downwardly on the collar 22. Slidable on the tube 21 is an externally threaded sleeve 83 having an external flange 84 at its upper end, the sleeve 83 normally resting on top of the sleeve 82 as shown in FIG. 9. In the screw release means 80, the expansive spring cage 47 has a lower collar 8d which is internally threaded so as to screw onto the externally threaded sleeve 83 as Vshown in FIG. 9. The threads on the sleeve 83 and lower collar are right hand threads whereby separation of the means 89 to release the jaws 30 for setting the anchor 15 in the well bore 17, is elfected by leftward rotation of the drill string 16. Such rotation, while the cage 47 remains motionless because of its contact with the well bore 17, results in unscrewing the externally threaded sleeve 83 `from the lower collar S5 as shown in FIG. l0 thus allowing the `head sub 18 to be withdrawn upwardly relative to the spring cage 47 with the resultant freeing of the detent jaws 3d and the subsequent setting of the anchor in the well bore.

After employing the screw release means Ell' to separate the jews 3d from the frusto-conical member 62 as shown in FIG. Z the next step, of lowering the drill string 1d to move these jaws downwardly over the member 62 as shown in FIG. 3 to expand the jaws into engagement with the walls of the well bore 17, is facilitated by the freedom of the externally threaded sleeve to slide upwardly'on the keys 81 and thus allow a substantial downward move- 6 ment of the mandrel tube relative to the spring cage 47 as illustrated in FIG. 1l.

In modern well drilling practice, the well bores frequently reach a depth of from 12,000 to 14,000` feet and the contour of such deep wells includes deviations from vertical and changes in direction to pass :around obstacles and these irregularities in the well bore tend to cause unanticipated and uncontrollable rotations of the drill string near the lower end thereof where testing` apparatus is incorporated therewith, for a deep testing operation. An anchor 1S included in such a testing apparatus might thus inadvertently be caused to set prematurely after the drill string had been lowered a long distance into the well thus requiring it to be withdrawn and reintroduced in order to reach the level at which it was desired to start the test. To prevent such a possibility, the present invention includes the provision of a hydrostatic lock 96 which includes a cylinder 91 having a central apertured head 92 at one end and a screw plug 93 for closing the opposite end. A plunger @d having an O-ring seal 95 and a compression spring 9e are trapped in the cylinder between the head 92, and the plug 93. The plunger has a short axial rod 97 formed integral therewith and extending through the apertured head 92 into a recess 9 provided in the wall of the anchor mandrel tube 21.

The cylinder 91 is secured in any suitable manner to the lower end of either the lower collar 49 or the lower collar so that when the anchor 15 is assembled at the top of the well before its being introduced into the well bore 17, the hydrostatic lock prevents either rotation or lengthwise movement of the expensive spring cage 47 relative to the mandrel tube 2l until the anchor 15 reaches a level in the well bore 17 where the hydrostatic pressure is suficient to force the plunger 94 inwardly in the cylinder 91 to compress the spring 96 and withdraw the axial rod 97 from the recess 93. The hydrostatic lock si@ thus automatically prevents any accidental or inadvertent operation of the anchor 15 (which might cause this to be set prematurely in the well bore into which it is being introduced) prior to its arrival at a level in the well bore which is close to the place where it is planned to be set to conduct a formation test.

After the automatic actuation above described of the hydrostatic lock 9d to release the spring cage l? from its locked relation to the mandrel tube 2l, the means heretorore described for normally setting the anchor 15 in the well bore may be employed by the operator at the top of the well, to accomplish this at the precise level desired.

As above noted, detent jaws Sil of varying length are employed in the anchor 15. The jaw length logically varies as a function or" the diameter of the `well bore 17. When the formation in which the anchor is to beset is of arrelatively` hard character so that the jaws 36 may not bite very deeply into this, jaws are employed with a length which will cause the jaws to attack the well bore wall at a more widely expanded angle. This makes a shallow bite into the formation give adequate support tov the anchor because of the tremendous pressure with which the jaws are expanded by `the toggle leverage with which the drill string weight is applied to said jaws.

A modified form of jaw Idil is shown in FIG. 8 which is just like jaw Sil excepting for the material forming the lower portion of the jaw being turned down, as at 191, thereby causing jaw lil@ to swing out at a slightly greater angle with the mandrel tube 21 before it engages the wall of the well bore. Moreover, the decreased diameter of the cutting edge M2 of jaw ltlll makes this jaw more readily penetrate the formation. Where the latter is especially dense, therefore, the use of jaws lull on the anchor 15 is recommended. Y

The claims are: j

1. In a selective formation zoneanchor, the combination of a head sub having a pair of diametrically opposed lugs extending downwardly from the lower end of said sub; a mandrel tube provided axially onrand extending downwardly from said sub; a pair of detent jaws which are pivotally connected respectively at their upper ends with said lugs and are adapted to have both retracted and expanded positions, said jaws when in retracted positions enclosing said tube to form a cylinder having approximately the same outside diameter as said head sub and being internally beveled at their lower ends; a locking spike provided in each of said jaws, said spikes extending downward in parallel relation from said jaws when the latter are in their retracted positions; expansive spring cage means slidably and rotatably mounted on said tube beneath said jaws, said means normally expanding into engagement with the bore of a well into which said anchor is introduced so as to trictionally resist longitudinal movement in or rotation in said bore; a member rotatably mounted on the upper end of said spring cage means and having very limited axial movement relative thereto, said member having an upwardly disposed conical face provided with parallel holes which are adapted to receive said jaw retaining spikes to retain said jaws in their retracted positions when said spring cage means is held shifted upwardly on said tube; and pin-and-J-slot means provided on said tube and said spring cage means for holding said conical member upwardly in jaw retaining relation with said jaw spikes when introducing said anchor into a well bore, but manipulatable by rotation of said head sub from the ground level to disconnect said pin-and-J -slot means after which said head sub may be pulled upwardly to withdraw said spikes from said holes in said conical member and then rotate said jaws to misalign said spikes with said holes and then lower said jaws to cause said spikes to engage said conical face thereby expanding said jaws outwardly into engagement with the wall of said well bore and set said anchor against downward movement in said bore.

2. A combination as recited in claim l wherein hydrostatic lock means are provided on said anchor which retains said detent jaws in their retracted positions until said Y anchor has reached a predetermined depth in the liquid in said well bore, said hydrostatic lock means yielding to the liquid pressure at that depth so as to no longer function to retain said detent jaws in retracted positions.

3. A combination as recited in claim 2 wherein said hydrostatic lock means embodies means for locking said spring cage means against rotation relatve to said tube while said `J-slot means is positioned so as to restrict longitudinal movement of said spring cage means relative to said tube whereby said conical member is maintained in locking relation with the spikes of said detent jaws.

4. A combination as recited in claim l in which said spring cage means includes upper and lower collars rotatably and slidably receiving said tube, said J-slot locking means being associated with said lower collar and said conical member having a swivel connection with Said upper collar; and a series of leaf springs bowed outwardly with their upper and lower ends secured respectively to said upper and lower collars.

5. In a selective formation zone anchor, the combination of: a head sub having a pair of diametrically opposed lugs extending downwardly from the lower end of said sub; a mandrel tube provided axially on and extending downwardly from said sub; a pair of detent jaws which are pivotally connected respectively at their upper ends with said lugs and are adapted to have both retracted and expanded positions, said jaws when in retracted positions litting together around said tube; a locking spike provided in each of said jaws, said spikes extending downward in parallel relation from said jaws when the latter are in their retracted positions; expansive spring cage means slidably and rotatably mounted on said tube beneath said jaws, said means normally expanding into engagement with the bore of a well into which said anchor is introduced so as to frictionally resist longitudinal movement in or rotation in said bore; a member rotatably mounted on the upper end of said spring cage means but having very limited axial movementrrelative thereto said member having an upwardly disposed conical face provided with parallel holes which are adapted to receive said jaw retaining spikes when said spring cage means is shifted upwardly on said tube to retain said jaws in their retracted positions; a male threaded element provided on said tube; and a female threaded element provided on said spring cage means, said elements having threaded engagement to hold said conical member in locking relation with said detent jaws when said anchor is introduced into a well bore, said threaded elements being disengageable by rotation of said sub from the ground level, the unscrewing of said elements permitting said sub to be drawn upwardly relative to said conical member whereby said detent jaws will be released for expansion as aforesaid.

6. A combination as recited in claim 5 in which said spring cage means is provided with a hydrostatic locking means which engages said tube and prevents rotation of said tube relative to said cage means until said anchor has reached a predetermined depth in the liquid contained within a well bore into which said anchor is being introduced. Y

7. in a selective formation zone anchor, the combination of: a head sub; a mandrel tube axially mounted on and extending downwardly from said sub; a pair of detent jaws which are pivotally connected respectively at their upper ends with said sub and are adapted to have both retracted and expanded positions, said jaws, when in retracted positions, iitting together around said tube, the upper portions of said jaws then combining to form a cylinder having substantially the same outside diameter as said head sub, the lower portions of said jaws having a substantially reduced outside diameter and being internally beveled at their lower ends; a locking spike provided in each of said jaws, said spikes extending downward in parallel relation from said jaws when the latter are in their retracted positions; expansive spring cage means slidably and rotatably mounted on said tube beneath said jaws, said means normally expanding into engagement with the bore of a well into which said anchor is introduced so as to frictionally resist longitudinal movement in or rotation in said bore; a member rotatably mounted on the upper end of said spring cage means but having very limited axial movement relative thereto, said member having an upwardly disposed conical face provided with parallel holes which are adapted to receive said jaw retaining spikes when said spring cage means is shifted upwardlyon said tube to retain said jaws in their retracted positions; and pin-and-J-slot means provided on said tube and said spring cage means for holding said conical member upwardly over said jaw spikes while said anchor is being introduced into a well bore, said pin-and-J-slot means being manipulatable by rotation of said head sub from the ground level to disconnect said pin-and-J-slot means after which said head sub may be pulled-upwardly to withdraw said spikes from said holes in said conical member and then rotate said jaws to misalign said spikes with said holes and then lower said jaws to cause said spikes to engage said conical face thereby expanding said jaws outwardly into engagement with the wall of said well bore and set said anchor against downward movement in said bore.

8. In a selective formation zone anchor, the combination of: a head sub; a mandrel provided on said sub and extending axially downward therefrom; a pair of detent jaws pivotally mounted on said head for swinging movement between retracted and expanded positions; expansive means shiftable axially on said mandrel, and normally frictionally engaging the wall of a well bore into which said anchor is introduced; and interlocking means on said jaws and said expansive means for locking said jaws in retracted positions when said expansive means is located in close vertical spaced relation with said jaws, so that downward movement ot said head, while said expansive means is supported frictionally by the Walls of a well bore, will maintain said locking relation, While lifting of said head sub and said jaws mounted thereon will increase the vertical space between said expansive means and said jaws and free the latter from said interlocking means whereby said jaws may be shifted from their retracted positions to their expanded positions and thus be caused to dig into the wall of said Well bore to support said anchor.

9. A combination as recited in claim 8 in which hydrostatic means is provided for locking said expansive means in close vertical spaced relation with said jaws and thus preventing the freeing of said jaws from said interlocking means until after said anchor has been lowered to a certain predetermined depth in the liquid in a well bore,

re said hydrostatic means then responding to the hydrostatic pressure at said depth to unlock said expansive means, whereby, lifting on said head sub will vertically separate said jaws and said expansive means and disconnect said interlocking means.

References Cited in the tile of this patent UNITED STATES PATENTS 2,333,305 Eckert Nov. 2, 1943 2,618,344 Turechek et al. Nov. 18, 1952 2,695,067 Smith et al. Nov. 23, 1954 2,711,220 Simmons June 21, 1955 

1. IN A SELECTIVE FORMATION ZONE ANCHOR, THE COMBINATION OF: A HEAD SUB HAVING A PAIR OF DIAMETERICALLY OPPOSED LUGS EXTENDING DOWNWARDLY FROM THE LOWER END OF SAID SUB; A MANDREL TUBE PROVIDED AXIALLY ON AND EXTENDING DOWNWARDLY FROM SAID SUB; A PAIR OF DETENT JAWS WHICH ARE PIVOTALLY CONNECTED RESPECTIVELY AT THEIR UPPER ENDS WITH SAID LUGS AND ARE ADAPTED TO HAVE BOTH RETRACTED AND EXPANDED POSITIONS, SAID JAWS WHEN IN RETRACTED POSITIONS ENCLOSING SAID TUBE TO FORM A CYLINDER HAVING APPROXIMATELY THE SAME OUTSIDE DIAMETER AS SAID HEAD SUB AND BEING INTERNALLY BEVELED AT THEIR LOWER ENDS; A LOCKING SPIKE PROVIDED IN EACH OF SAID JAWS, SAID SPIKES EXTENDING DOWNWARD IN PARALLEL RELATION FROM SAID JAWS WHEN THE LATTER ARE IN THEIR RETRACTED POSITIONS; EXPANSIVE SPRING CAGE MEANS SLIDABLY AND ROTATABLY MOUNTED ON SAID TUBE BENEATH SAID JAWS, SAID MEANS NORMALLY EXPANDING INTO ENGAGEMENT WITH THE BORE OF A WELL INTO WHICH SAID ANCHOR IS INTRODUCED SO AS TO FRICTIONALLY RESIST LONGITUDINAL MOVEMENT IN OR ROTATION IN SAID BORE; A MEMBER ROTATABLY MOUNTED ON THE UPPER END OF SAID SPRING CAGE MEANS AND HAVING VERY LIMITED AXIAL MOVEMENT RELATIVE THERETO, SAID MEMBER HAVING AN UPWARDLY DISPOSED CONICAL FACE PROVIDED WITH PARALLEL HOLES WHICH ARE ADAPTED TO RECEIVE SAID JAW RETAINING SPIKES TO RETAIN SAID JAWS IN THEIR RETRACTED POSITIONS WHEN SAID SPRING CAGE MEANS IS HELD SHIFTED UPWARDLY ON SAID TUBE; AND PIN-AND-J-SLOT MEANS PROVIDED ON SAID TUBE AND SAID SPRING CAGE MEANS FOR HOLDING SAID CONICAL MEMBER UPWARDLY IN JAW RETAINING RELATION WITH SAID JAW SPIKES WHEN INTRODUCING SAID ANCHOR INTO A WELL BORE, BUT MANIPULATABLE BY ROTATION OF SAID HEAD SUB FROM THE GROUND LEVEL TO DISCONNECTED SAID PIN-AND-J-SLOT MEANS AFTER WHICH SAID HEAD SUB MAY BE PULLED UPWARDLY TO WITHDRAW SAID SPIKES FROM SAID HOLES IN SAID CONICAL MEMBER AND THEN ROTATE SAID JAWS TO MISALIGN SAID SPIKES WITH SAID HOLES AND THEN LOWER SAID JAWS TO CAUSE SAID SPIKES TO ENGAGE SAID CONICAL FACE THEREBY EXPANDING SAID JAWS OUTWARDLY INTO ENGAGEMENT WITH THE WALL OF SAID WELL BORE AND SET SAID ANCHOR AGAINST DOWNWARD MOVEMENT IN SAID BORE. 